Use the Djblets MySQL backend in Review Board.
Review Request #8641 — Created Jan. 20, 2017 and submitted
Djblets just gained a new and improved MySQL backend. This change updates Review Board to make use of it when the standard Django MySQL backend is configured. settings.py now scans the database backends that are configured, looking for the Django MySQL backend. If found, the backend is swapped out for the Djblets one, requiring no change in the server's configuration.
Tested with a standard Django MySQL backend in settings_local.py. Saw
that the Djblets backend was activated.